Small Modular Reactor

Small modular reactors (SMRs) are a proposed class of nuclear fission reactors, smaller than conventional nuclear reactors, which can be built in one location (such as a factory), then shipped, commissioned, and operated at a separate site. The term SMR refers to the size, capacity and modular construction only, not to the reactor type and the nuclear process which is applied. Designs range from scaled down versions of existing designs to generation IV designs. Both thermal-neutron reactors and fast-neutron reactors have been proposed, along with molten salt and gas cooled reactor models.

SMRs are typically anticipated to have an electrical power output of less than 300 MW_e (electric) or less than 1000 MW_th (thermal). Many SMR proposals rely on a manufacturing-centric model, requiring many deployments to secure economies of unit production large enough to achieve economic viability. Some SMR designs, typically those using Generation IV technologies, aim to secure additional economic advantage through improvements in electrical generating efficiency from much higher temperature steam generation. Ideally, modular reactors will reduce on-site construction, increase containment efficiency, and are claimed to enhance safety. The greater safety should come via the use of passive safety features that operate without human intervention, a concept already implemented in some conventional nuclear reactor types. SMRs should also reduce staffing versus conventional nuclear reactors,"The Galena Project Technical Publications"
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While there are dozens of modular reactor designs and yet unfinished demonstration projects, the floating nuclear power plant Akademik Lomonosov (operating in Pevek in Russia's Far East) is, as of October 2022, the first and only operating prototype in the world. Construction of the world's first land-based SMR began in July 2021 with the Chinese power plant Linglong One ( zh, 玲珑一号); this prototype is due to commence generation by the end of 2026.

SMRs differ in terms of staffing, security and deployment time. US government studies to evaluate SMR-associated risks have slowed licensing. One concern with SMRs is preventing nuclear proliferation.

Background

Economic factors of scale mean that nuclear reactors tend to be large, to such an extent that size itself becomes a limiting factor. The 1986 Chernobyl disaster and the 2011 Fukushima nuclear disaster caused a major set-back for the nuclear industry, with worldwide suspension of development, cutting down of funding, and closure of reactor plants.

In response, a new strategy was introduced aiming at building smaller reactors, which are faster to realize, safer, and at lower cost for a single reactor. Despite the loss of scale advantages and considerably less power output, funding was expected to be easier thanks to the introduction of modular construction and projects with expected shorter timescales. The generic SMR proposal is to swap the economies of unit scale for the economies of unit mass production.

Proponents claim that SMRs are less expensive due to the use of standardized modules that can be produced off-site. SMRs do, however, also have some economic disadvantages. Several studies suggest that the overall costs of SMRs are comparable with those of conventional large reactors. Moreover, extremely
limited information about SMR modules transportation has been published. Critics say that modular building will only be cost-effective at high quantities of the same types, given the still remaining high costs for each SMR. A high market share is needed to obtain sufficient orders.

Proponents say that nuclear energy with proven technology is safe; the nuclear industry contends that smaller size will make SMRs even safer than conventional plants. Critics say that more small reactors pose a higher risk, requiring more transportation of nuclear fuel and increased generation of waste. SMRs require new designs with new technology, the safety of which has yet to be proven.

Until 2020, no truly modular SMRs had been built. In May 2020, the first prototype of a floating nuclear power plant with two 30 MW_e reactors - the type ''KLT-40